[gradsusr] Different output values from Grads and wgrib2

Mon Oct 24 15:18:21 EDT 2011

Dear All, 
This thread has eventually revealed that there is indeed a bug in gribmap: for z-varying variables, the check for matching level types was overlooked, and resulted in an inaccurate match. That is why the temperature between the 0-30mb layer was mistakenly being displayed as the 30mb temperature. This is a significant bug, because it gives the user incorrect data with no indication of any error, so I am going to put out a new release as soon as I can. 
--Jennifer

On Oct 21, 2011, at 4:43 PM, Jennifer Adams wrote:

> I think the data file is corrupted. I can duplicate the error, but the other diagnostic tools (wgrib2 and grib2scan) throw errors when trying to read that file. 
> --Jennifer
> 
> On Oct 21, 2011, at 1:17 PM, Wesley Ebisuzaki wrote:
> 
>> Bo,
>> 
>>  I compared your ctl file with mine and they were the same except for the location of the files (dset/index/comments).
>> 
>>  Maybe it's a problem with gribmap.  Perhaps gribmap is confusing the 30mb TMP with another field.  Try running
>> 
>>  gribmap -v -i test.ctl
>> 
>> 
>>             Wesley
>> 
>> 
>> Bo Zhang wrote:
>>> Hi Wesley,
>>> 
>>>    Since John tried and found the same problem. Perhaps, some issue happens during control files generation. Could you please send me the control files you create and may be g2ctl also.
>>> 
>>>    I have tried both GrADS2.0 and 2.0.a9 on my machine which all have this issue.     My OS: Red Hat Enterprise Linux Server release 5.6 (Tikanga).   
>>> Bo Zhang
>>> Dow 824,Civil and Environmental Engineering
>>> Michigan Tech University
>>> 1400 Townsends Drive. Houghton, MI, 49931
>>> 
>>> ----- Original Message -----
>>> From: "Wesley Ebisuzaki" <Wesley.Ebisuzaki at noaa.gov>
>>> To: "Bo Zhang" <bzhang3 at mtu.edu>
>>> Sent: Thursday, October 20, 2011 4:40:13 PM (GMT-0500) Auto-Detected
>>> Subject: Re: Different output values from Grads and wgrib2
>>> 
>>> Bo,
>>> 
>>>    With your file, I get the right number for 30 mb with GrADS installed on my
>>> machine. (64-bit RedHat 5 - linux, GrADS 2.0a9 from the COLA site).
>>> 
>>>    The problem that you are finding may be version / machine specific.  You
>>> should send to the GrADS list
>>> 
>>>   (1) OS
>>>   (2) version of GrADS
>>>   (3) who compiled the GrADS or where obtained from
>>> 
>>>             Wesley
>>> 
>>> 
>>> 
>>> Bo Zhang wrote:
>>>  
>>>> Hi Wesley,
>>>> 
>>>> It seems my space is not working correctly, the file broken when John downloaded it. So, excuse me for sending you the data file directly. Here is my results of running GrADS on this data file. 
>>>> With wgrib2:
>>>> [bzhang3 at flexruns wgrib2]$ ./wgrib2 /home/campus03/bzhang3/Grads/fnl_20100508_06_00 -match TMP -s -ijlat 181 91
>>>> 3:120296:d=2010050806:TMP:10 mb:anl::(181,91),lon=180.000000,lat=0.000000,val=239
>>>> 8:393851:d=2010050806:TMP:20 mb:anl::(181,91),lon=180.000000,lat=0.000000,val=220.5
>>>> 13:666758:d=2010050806:TMP:30 mb:anl::(181,91),lon=180.000000,lat=0.000000,val=215.5
>>>> 18:961202:d=2010050806:TMP:50 mb:anl::(181,91),lon=180.000000,lat=0.000000,val=204.5
>>>> 23:1271647:d=2010050806:TMP:70 mb:anl::(181,91),lon=180.000000,lat=0.000000,val=193.7
>>>> 
>>>> With GrADS
>>>> [bzhang3 at flexruns bin]$ ./grads
>>>> ga-> set lat 0
>>>> LAT set to 0 0 ga-> set lon 180
>>>> LON set to 180 180
>>>> ga-> d tmpprs (lev=10)
>>>> Result value = 239  ga-> d tmpprs (lev=20)
>>>> Result value = 220.5 ga-> d tmpprs (lev=30)
>>>> Result value = 300.9 ga-> d tmpprs (lev=50)
>>>> Result value = 204.5 
>>>> All numbers match except at level of 30mb. I don't think the problem is from the data file since wgrib2 gives correct numbers. I use g2ctl and gribmap packed in GrADS to generate .ctl and .idx files. I am not sure my GrADS version, probably CentOS 5.6. Information on GrADS:
>>>> 
>>>> Grid Analysis and Display System (GrADS) Version 2.0.0
>>>> Copyright (c) 1988-2011 by Brian Doty and the
>>>> Institute for Global Environment and Society (IGES)
>>>> GrADS comes with ABSOLUTELY NO WARRANTY
>>>> See file COPYRIGHT for more information
>>>> Config: v2.0.0 little-endian readline printim grib2 netcdf hdf4-sds hdf5 opendap-grids,stn geotiff shapefile
>>>> 
>>>> Thanks.
>>>> 
>>>> Bo Zhang
>>>> Dow 824,Civil and Environmental Engineering
>>>> Michigan Tech University
>>>> 1400 Townsends Drive. Houghton, MI, 49931
>>>>    
>>> 
>>>  
>> 
>> dset ^fnl_20100508_06_00
>> index ^fnl_20100508_06_00.idx
>> undef 9.999E+20
>> title fnl_20100508_06_00
>> * produced by g2ctl v0.0.8.3
>> * command line options: fnl_20100508_06_00
>> * griddef=1:0:(360 x 181):grid_template=0:winds(N/S): 
>> dtype grib2
>> ydef 181 linear -90.000000 1
>> xdef 360 linear 0.000000 1.000000
>> tdef 1 linear 06Z08may2010 1mo
>> * PROFILE hPa
>> zdef 26 levels 100000 97500 95000 92500 90000 85000 80000 75000 70000 65000 60000 55000 50000 45000 40000 35000 30000 25000 20000 15000 10000 7000 5000 3000 2000 1000
>> options pascals
>> vars 1
>> TMPprs    26,100  0,0,0 ** (1000 975 950 925 900.. 70 50 30 20 10) Temperature [K]
>> ENDVARS
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> 
> --
> Jennifer M. Adams
> IGES/COLA
> 4041 Powder Mill Road, Suite 302
> Calverton, MD 20705
> jma at cola.iges.org
> 
> 
> 
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--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org

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